Oh, the previous owner of this bike was truly incompetent:
-- Right side mirror was forced (somehow) into the left perch, despite being left-hand threaded; left side mirror was attached to the right side of the handlebars on a clamp, since (of course) it didn't fit the perch.
-- Battery positive connection was floating; the screw was in the hole, but not threaded into the nut. Pretty sure it's not the proper battery either... seems a bit short (top to bottom) for the battery compartment.
-- Sealed beam in the headlight wasn't aligned in its ring properly, nor was the rubber part lined up correctly (the rubber didn't line up with either the bumps on the sealed beam NOR the voids in the ring). Also, the nuts and bushings from the headlight pivot mount (the bit that lets you adjust the sealed beam left-to-right) were floating loose in the headlight bucket.
WITH THAT SAID, I don't think the retorque has fixed the oil leak. Maybe, maybe it's slowed a bit, but not stopped, nor even slowed as much as I hoped. Gah. Retorquing the head was a lot easier than I expected though. I can't really tell if the current leak is actually the head gasket, or if it's the base gasket, as there is so much oily crud from the head gasket to the base gasket on the left side of the cylinders.
I've also discovered the forks are twisted a bit. Any words of wisdom here? Long long ago, when I weighed roughly half what I do now, I owned an XL125 Honda, and if I dropped it, the forks would twist. Then I'd just roll it up next to a tree or telephone pole and twist it back the other way, and everything was fine. I haven't tried it yet on my XS... any chance that will work? If not, how to go about it?